(1) Field of the Invention
The present invention relates to a process for firing ceramic shaped bodies, particularly, ceramic honeycomb structural bodies, and to a firing kiln adapted for effecting such a process.
(2) Related Art Statement
Heretofore, a tunnel kiln as shown in FIG. 4 has been used for firing ceramic honeycomb structural bodies from the standpoint of mass productivity. The tunnel kiln is generally constituted by a preheating zone 11, a firing zone 12, and a waste heat zone 13. Combustion gases generated from combustion burners 14 provided at the firing zone 12 are evacuated outside the kiln through the preheating zone 11 by suction forces of an exhaust fan 15 provided at a low temperature section of the preheating zone 11 on the inlet side. In the tunnel kiln of this structure, as shown in FIG. 5, the firing condition is constituted by a temperature-rising section, a sintering section in which a constant temperature is maintained, and a temperature-descending section.
However, if ceramic shaped bodies are fired under such firing conditions, firing cracks or deformation occur in some of fired products. In particular, occurrence of such defects is more frequent in the case of ceramic honeycomb structural bodies having a number of through holes.